Method of making spark-plugs



J. H. BECKER.

METHOD. OF MAKING SPARK PLUGS. APPLICATIONEILED JUNE 11. 1919.

1i, 331,091. Patented Feb. 17,1920.

" great during the manufacturing operation.

UNITED STATES rATEnroFFroE.

JOHN H. BECKER, or nu'r-IinYf-nnw JERSEY.

summon or Magritte srnax-rnues.

Application 4 a ,1 To all whom it may concern:

Be it known that 1, JOHN H. BECKER, a

citizen of the United States, and a resident of Nutley, Essex county,New Jersey, have invented, a new and useful Improvement in Methods. OfMaking Spark-Plugs, of which the folldwing is a full, clear, and exactdescription.

Myinvention relates to improvements in the :method of making sparkplugs, and more particularly in the method of securing the core orporcelain in the outer or metallic shell. Owing to the differentco-expansions of spark plug cores and their shells, there is a good dealof difiiculty in making a perfectly tight union between the parts especially Where attempts to do this are made without using gaskets, nuts,or the like. These extraneous fastenings are objectionable because inactual use when the plug becomes highly heated it often happens that thecore breaks because of the stress upon it (between its fasteningdevices, and Where the core is fastened by simply shrinking the metalupon it the loss by breakage is very It is generally recognized that itis desirable to have the core secured in its shell Without anyextraneous fastenings, but simply by having the shell shrunk upon thecore. My

invention provides a means for doing this so that the loss duringmanufacture is negligible, and therefore my method is such that afterthe plug is made it is not liable to break, because the core is;subjected to more strain during the process of manufacture than it everis in actual use. My method, therefore, is intended to provide asimpleand efiicient means of securing the core in the shell sothat it willstand up under use, and so that a perfect union between the two partswill be had.

Reference is to be had to the accompany- I ing drawing forming a part ofthis specification, in which similar reference characters indicatecorresponding parts in the vi w.

The drawing is a vertical section of a spark plug shell and core.

The shell 10 can be of any approved constrhction but it should have aslightly tapering? section 11,- "and the core 12 can likewise be offanusual or preferred construction,

- except t at it should have a section-'13 shaped to fit tight againstthe correspond ing part ,11 of the shell. -In my early at-' tempts toshrink ashell of this character Specification of Letters Patent..Patented Feb, 1'1. 1 920.

filed June 11, 1919. Serial No 303,372. I

upon a'somewhat similar core, I found that the breakage of thecorefranashigh as 95%; but by carrying out my method'as I have evolved it byrepeated experiments, the breakage is practically nothing, and the unionbetween the shell and core is perfect so that no other fastening meansis necessary. .To accomplish this result I practically annealthe core,that is to say, I expel all the moisture practicable, and toughen it bysubjecting it for a comparatively long time to a heating but relativelylow temperature. I have got the best results baking the core in an ovenfor about fifty hours at a temperature of about 150 degrees F. Theheating process may be made longer or shorter, but the time given givesthe best results. Likewise the temperature can-be varied somewhat, butshould not be varied much from the temperature given. In any event thetemperature should not be less "than 140 degrees or more than 170degrees.

' After the core has been toughened by the long preliminary treatment asspecified, and

.it is to be united permanently to the shell,

the latter is heated to a cherry red heat, that is to say, to atemperature of approximately shell so that the part 13 Will seat itselffirmly in the part 11 of the shell, and then the shell is permitted toshrink by cooling so as to become absolutely fixed upon the core.

If this method is carried out as stated there will be comparatively noloss of cores by breakage, and the two parts Will'be so firmlyunited'that they will never separate under use, and moreover, the jointwill be so tight that there will be no leakage of gas or current.

I claim 1. The herein described method of securing spark plug cores intheir shells, which consists in first toughening the core by subjectingit for a comparatively long time to a low temperature ,'then heating theshell and core to approxlmately the same temperature, andfinalljyngyhile both shell and core are hot, pressing the core into itsseat in the shell. 1

l {2. The herein described method of securing spark plug cores in theishells, which oonsists in first tonghening the core by a longpreliminary heating at a relatively low temperature, then heating thecore and shell to a high temperature, and finally pressing the hot coreto its seat in the hot shell. 3. The herein described method of securingspark plug shells and cores, Whicheonsists in first toughening the coreby heating it for a long period to a temperature of not less than 140degrees F. nor more than. 170 degrees, next heating the shell and coreto a high temperature, and finally pressing the hot core into the hotshell. 7

4:. The herein described method of: secur-i ing spark plug cores andshells, Which consists in. first toughening the core by a longpre-l1eati11g at a ow temperature, next heating both core and shell to atemperature of :not less than 1200 degrees nor more than 1600 degreesFt, then pressing the hot core to its seat in the hot shell, and finallycooling the united parts so that the shell shrinks tipon the core.

$3 5. A herein described method of uniting the hot core to its seat inthe hot shell.

JoHNii, BECKER.

Witnesses:

WARREN B. HU'roHmsoN, M. G. ODONNELL.

shell to a high temperature, Y

spark plug shells and cores, Which consists in providing the shell Witha tapering-seat,

